The present invention is distinguished from other control systems such as flame rectifiers, photocell systems, and spectroscopic analyzers, which provide a means for detecting the ignition of fuel in a combustion device. Flame rectifiers such as described by Smith, et al., U.S. Pat. No. 2,748,846, and by Serber, U.S. Pat. No. 4,405,299 have been used for obtaining response to flame failure, but these systems are expensive, require external power and have maintenance problems due to corrosion. Ito, et al., U.S. Pat. No. 3,765,820 describe a combustion apparatus having a gas heated element disposed within, and projecting above, a burner plate. The light emitted from the luminous element is detected by an externally powered photosensing circuit and is used to control the efficiency of combustion. A similar method is described by Gulitz, U.S. Pat. No. 4,059,385. None of these methods provide proof-of-ignitability detection.
Walbridge, U.S. Pat. No. 3,537,804 describes the use of a photoelectric element that senses radiation emitted by a hot-wire igniter. The circuitry can be used to regulate the flow of fuel or the temperature of the igniter. French patent No. 76-20296 describes an emissive ignition coil located above a quartz rod connected to a fiber optic which performs in a manner to control the burner as well as ignition. Other flame detecting devices have been described using emissive means and optical sensing mechanisms including the Japanese patent of Kurosawa, No. 55-51230. N. Mitsugu received a Japanese patent, No. 52-30921, on a similar flame detecting device designed to prevent problems with soot.
Ryno, U.S. Pat. No. 4,131,413 describes a self-contained spark igniter activated by a storage battery rechargeable by multiple thermopile generators.
A need exists for a failsafe control mechanism that is faster and more reliable than the devices described in the prior art and which can power a solenoid fuel intake valve as well as power its own electronic circuits. It is desirable that there be no possibility of fuel flow before there is proof that such fuel will ignite.
This invention provides an apparatus and method which accomplishes these goals at reduced costs. This invention involves several novel embodiments of our earlier patent application No. PCT/US 84/101038 filed July 3, 1984, and puts forth several new uses and improvements, e.g. combining our new proof of ignitability and proof of ignition features with our earlier carbon monoxide safety, fast shutoff invention.